Television



Nov. 4, 1941. P. c, GOLDMARK 1 2,231,848

' TELEVISION i :Filed April 1, 193e 2 sheets-sheet 1 @JW i HMHHH;

, u@ illlll! NOV 4'941 P. cfGoLDMARK A 2,261,848

TELEvIsIvoN l Filed April l, 1956 v2 Sheets-Sheet 2 ATTORNEYS Patented Nov. 4, 1941 Peter C. Goldmark, Brooklyn, N. Y., assignor to Markia Corporation, New York, N. Y., a corporation of New York Application April 1, 1936, serial No. '12,009 v (ci. irs- 1.2)

25 Claims.

This invention relates to a television transmitting system and more particularly to a system whereby pictures on a cinematographic film may be televised while the film is being constantly moved.

An object of the invention is to provide -a suitable method and apparatus for scanning such film in a manner giving a standard number of lines and frames per second while utilizing commercial alternating current or other periodic actuating eld as the source of power that has a frequency different from the number of frames per second desired.

Another object is to achieve interlaced scansion of a constantly moving film in a manner giving a standard number of pictures, for example, 24 frames per second, when actuated with alternating current having-a. frequency of 60 cycles per second.

A further object is to provide a suitable scanning oscillator for a cathode ray tube which gives a saw-toothed scanning current having cyclic irregularities. A still further object is to provide a scanning oscillator for a cathode ray tube which gives a periodic line shifting potential whereby interlaced scanning maybe practiced.

Other objects of the invention will in part'be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation of oneI or more of such steps with respect'to each of the others, and the apparatus embodying features of construction, combinations of elements and arrangements of parts, which are adapted to eiect such steps. 'all as exemplied in the following detailed disclosure, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature an objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawings, in

which:

Fig. 1 is a view partly in perspective and partly schematic, showing a device for vtransmitting a facsimile of a picture on a film, in accordance with theinvention;

Fig. -2 is a fragmentary view showing the man ner in which interlaced scanning may be accomplished in connection with the practice'of the invention;

'effects the desired movement of vthe scanning light spot; and

4 is a schematic view illustrating the principle by which scansion is effected of a. moving lm by means of the light spot moved under the control of Vthe screen shown in Fig 3.

The use of a so-called intermediate lm in the process oftelevising a scene of action, such as a football game, for home reception or for immediate reproduction in theaters, halls, -and the like, is desirable, because it obviates the limitations heretofore imposed by the available illumination.

The scansion of such a film for/reproduction with standard apparatus, is in vitself a problem,

assuming suicient illumination. It is now standardpractice to scan pictures to be televised at 24 nlm frames per second, but the available actuating fields, such as commercial alternating current, for operating the television apparatus, as' a rule, are standardized at some other frequency, for example, at 60 cycles per second,

which is not a multiple of the number of frames desired. The operation and synchronization of I standard equipment to effect the scansion of a moving film from such source of power was consequently heretofore regarded as not feasible.

By the present invention, al ready method of scansion is provided whereby a nlm while in motion may be scanned at the rate of 24 lm frames a second and 60 field scansions per second, thereby enabling commercial 60 cycle alternating current to be employed without producing moving hum patterns. To this end, a moving light spot may be employed to give a scanning beam or ray which is modulated by 'traversing the film to be scanned, the modulated ray resulting being proj ected into a suitable device that responds photoelectrically, such as a photoelectric cell, and the electric impulses had therefrom employed to modulate a carrier that is broadcast. As will be v understood, the cathode ray tube employed is Fig. 3 Vis an enlarged development of a light screen employed for regulating the admission of light to the scansion current generator which one form of an electronic scanning device.`

By the present invention, the motion of the light spot, which may be produced inany suitable way, for example, from the illumination produced on a iluorescent screen by the impingement of a cathode ray in a cathode ray tube, is controlled and oscillated in one direction, f or example, horizontally, ata relatively high fre` quency in order to scan line elements of the picture while it is also shifted in the other direction, that is, vertically, in an irregular` manner during a prearranged cycle or period to achieve two effects, namely, first a gradual-shiftlng of the light spot simultaneously with the achieve this latter in conjunction with the'i method of the present invention, it is proposed to send out a relatively sharp impulse with frame frequency that will effect a small shift up or down cyclically of the light spot whereby the interlaced scansion effect is had.

The means for achieving the desired movement of the light spot ccmprise special forms of oscillating generators that supply oscillating current to the cathode ray tube, such generators being under the control of a master `device that is actuated 4by the commercial source of alternating current. A convenient form of master controller for this purpose utilizes photoelectric ,actuating means, and, to this end, has a special form of light regulating screen that is moved between the light source, or sources, as the case may be, and the photocells of the actuating means by an electric motor driven by the commercial alternating current.

Referring now to the drawings, and particularly to Fig. 1, IIJ denotes a portion of the film being scanned and is shown as disposed for vertical movement and threaded over driving sprockets II which are driven at a suitable constant speed, by-suitable means, for example, by a motor I2, shown as geared to the sprockets. A cathode ray tube I3 is arranged to provide a suitable scanning eld over which the `film I0 is passed and scanned by the light spot produced by the cathode ray Within the tube. 'I'he light spot is focused on the vertical portion of the film by a suitable,` optical means, here depicted as a lens I4, the modulated light which traverses the film being picked up by another optical means, here depicted as a lens I5, and projected into a photoelectric cell 1 I B. .This latter is connected to an amplifier for modulating the carrier, generated by an oscillator I8, and coupled to an antenna I9. It will therefore be seen that the electronic scanning tube I3 is in conjugate relation with the film I0.

When the film is moved vertically downwardly, as depicted in the drawings, the scansion of the line elements of the picture is effected by movv`ing the light spot horizontally. Accordingly, the

cathode ray tube I3 is shown as provided with deecting plates 2I and 22 disposed on opposite lsides of the tube, the plates being connectedto becharged by a suitable saw-toothed oscillating potential supplied by the oscillator 20.

In order to achieve vertical shifting of the light spot, as indicated above, the cathode ray tube is also provided with deflecting plates 23 and 24 in planes at right angles to the plates 2| and 22.A

'I'hese plates are connected to receive actuating charges from an oscillating amplifier 25, which latter is under the control of the master controlling device which comprises a screen 26 on a rotating transparent disk 21, the disk being rotated by a synchronous electric motor 28 that is supplied from standardl commercial mains, here indicated as cycle mains. A mask 29 is also interposed between the disk and the light source 2,261,848 motion of the slm, and second a jump ef the nght 30; the mask being slotted, as indicated at 29 in order to admit and sharply direct the beam of light which passes into a photoelectric cell 3|;

this latter being electrically connected to control the amplifier 25. The light admitted to the photocell 3I is regulated by the motion past the slit 29' of a specially shaped opening 26a in the screen 26, this opening preferably having a contour of a character adapted to follow the movement of the lm and give the desired oscillating current; the development of a suitable contour being depicted in Fig. 3.

In Fig. 3, the opening 26a has a base line AB, with ordinates drawn upwardly therefrom that define an opening that determines the quantity and, consequently, the intensity of the light admitted; the abscissae denoting instants of the time at which the light enters with the rotation of the disk. It is thus seen that the screen may be laid out on disk 21 by changing theordinates of Fig. 3 to radii, the abscissae to circles, and the oblique lines to arcs of Archimedan spirals. The serrated opening 26a operates to regulate the passage of light with the passage of time to eiect sudden changes thereof to cause the shifting of the scanning light spot desired; this regulation being coordinated with the position ofthe picture-frame being scanned. The coordination is achieved by laying off the ordinates of the opening at 25a to regulate light for actuating the oscillator in relation to the film moving events, as illustrated by the relation of Fig. 3 to Fig. 4. It will, of course, be understood that the development of Fig. 3 may be applied without alteration to the surface ofI a revolving drum, when used as a substitute for the disk here shown.

To lay out the nlm moving events, a distance :r1-x2 is' marked off along the time coordinate-in of a value which is the greatest comr'non divisor of the alternating current frequency and the 'frame frequency;` Hence,"the'number of frames Vmoved times the number of transit periods in a second gives the desired number of frames per second. A suitable transit period is indicated as Period I and Period II, along the axis .t1-Ga, and represents 112th second and comprises ve field scanning periods. This is equal to five A. C. cycles and hence moving A. C. hum patterns are avoided, as will be understood. In the transit period, two frames pass completely across the field scanned, i. e., from the full view position where .two frames are completely above the reference line to a fully passed position where the two frames are completely below the reference line.

During the nrst unassuming period, the 111m will have moved from the position shown at C-I-I in the first transit period down a distance-which equals 2/sths of a frame-height at the inception of the second field-scanning period of the first transit period. This is shown at C-I-I desired number of times,

rality of times inthe direction of travel of the film within a cycle. It will also be note that the difference betwee the -distance the lm moves in a eld-scanning period (%ths the lmframe height) and the height of the scanning area (%ths the film-frame height) is %th the height of a film frame, and hence -is substantially different from, the height of the scanning area:`

To move and shift the light spot during the scanning periods in the manner above described,

, the scansion oscillator is made to supply sawhave put in the desirednumber of lines, when the top of the lm frame, which has been moving down, is reached; inother words, to scan the lower lm frame, the light spot starts from position P1, putting in lines and moves up only the so as to finish at point Fi. With the above line frequency, 171 lines will be scanned. At this juncture,` the iight spot is made to drop to a new starting position P2 when it traverses the same film frame a second time during the second eld-scanning period. The light spot is here permitted only suicient upward motion to put in its 171 lines when thetop of the film frame is reached, i. e., when it has moved up another distance h it nishes. at point Fa. At this juncture the light spot is again dropped to a third starting position Pa but this time when the lower nlm frame has been scanned, the light spot continues upwardly for another field-scanning period, in order to scan the upper film frame.

AIn other words, the finishing position Fs for the lower film frame in the third field-scanning period is the starting position for the upper lm frame in the fourth eld-scanning period. At the end of the fourth field-scanning period, when the light; spot has moved up a distance 2h from the position P3 and has reached position F4, the light spot is dropped to a position P4 where it begins to scan the upper film frame a second time. At the end of the fifth eld scansion the Vlight spot will have reached a position Fs which corresponds to the starting position for the second transit period.

It will be seen, therefore, from Fig. 4 and the Vabove description thereof, that a two-dimen- V sional scanning pattern is produced by the scanning tube I3l and scans a scanning area in the path of travel ofthe film `:roth laterally and longitudinally of the lm in lines extending laterally thereof. During the rst eld-scanning.

` period the scanning area extends longitudinally from the line beginning at P1 to the line ending at Fi. The height of this scanning area in the specific example of Fig. 4 is %ths of the filmframe height. This scanning area is then displaced by a distance equal to %ths of the filmframe height for the second eld scansion, so as to begin scansion at P z. This displacement is, therefore substantially different from the height distancel h during the period of a eld scansion,

toothed oscillating current of a frequency of 10260 cycles per second to the plates 2| and 22 .for effecting horizontal movement. The arrangement employs a set of cascade amplifiers' 33, 34 and `3 5 associated with theo'scillator 20 whichlis preferably of the tube variety and overbiased, the wholebeing triggered off by impulses had from the photocell' 31. To this end, a second light source.30 is shown emitting light controlled by a series of slots 36 laid oif in the screen 26 above opening 26a.' It is seen that the oscillating frequency is a harmonic of 60 and may be had from 60 cycle current impulses, provided the disk is driven by a synchronous motor driven from 60 cycle mains, as shown, and has the slots 36 on the ordinates demarking A. C. cycles on of the scanning area that the longitudinal rate of scanning is adapted to produce in a complete yeld-scanning period. A similar displacement is produced between the scanning areas of field scansionsl '2-3 and 4-5, so that a plurality of displacements occur withina cycle. At the end Aof field scansion 5, the cycle begins over again. In the specific embodiment of Fig. 4, the displacements are such that the scanning areas of successive eld scansions I-2, 2--3 and 4 5, overlap by an amount equalto 6th of the film-v frame height. Also, the longitudinal scanning is opposite to the direction of movement of the film, and the scanning area is displaced a piuthe screen 26. `The design of the synchronous motor is, of course, to beconsidered in this connection and a proper number of poles provided.v Thismay b e readily determined with the aid of the following formula, where p denotes the number of pairs of -poles to be employed, and

r, the number of transit periods on the disk n, the revolutions per second of disk h, the number of film frames completely scanned during a transit period r, (1:6011) the revolutions per minute of disk f, the frequency of available alternating current,

o-r actuating field q, the film frame frequency.

Then itis seen that nh=d and 1L=f/p consequently 4quency of the 180 cycles per second. Thisin turn is arranged to actuate the second stage amplifier 34 from which another third harmonic may be had, i. e., the ninth harmonic of the fundamental, giving a frequency of 540 cycles per second. The third stage 35 is then arranged to give the nineteenth harmonic of the fundamental, i. e., a frequency of 10260- The longitudinalmovement of the light spot desired is effected by oscillating current supplied to the plates 23 and 24 from the oscillating amplifier 25 which has its characteristic controlled by Ythe light admitted through opening 26a. To effect an .upward movement of the light spot e 1) Hence for f=60, h=5 and 1:60, Equation 1 gives through a distance h, a charging current that increases linearly is applied for `560th of a second. This is achieved by admitting light that increases linearly in intensity to a maximum value at the end of the first field scanning period, when it is suddenly decreased to a value giving the vnew starting point of the second neld scanning period. To obtain this regulation of the light. the opening 26a is laid out with a base line AB, which is to be traversed by the light source in the transit have a base line A'B' period of th second corresponding to the five field scanning periods of Fig. 4. The opening is given a height AC to admit light 'of an intensity that gives a charge to move the light spot to position P1. An oblique line CD is drawn to effect the linear increase inthe intensity of the light diu'ing the first field scanning period, this increase being terminated with an ordinate DE that drops to a point below C, in order to eect the desired drop of the light spot at the end of the first field scanning period.

From a consideration of Fig. 4, it is seen that the light intensity must be capable of being decreased by at least fourunits, that may be arbitrarily-chosen, from that admitted by the slot 29 when restricted by the opening AC. Also, the drop inthe light spot to be'effected by cutting the intensity or the light to the value admitted at E, ymay be produced by reducing the light two units.y The distance AC is then made four of these arbitrary units high; the distance EE' two units high; and the distance EDve units, since the distance h is but %ths of a.frameheight, or three units out of the total of four which the light spot drops. A

The line EG is drawn obliquely to a .point three units above E, to effect the upward movement of the light by another distance h and then terminated with an ordinate reaching .to a point H in the base line. AB. From` H an oblique line is drawn to K which spans a distance equal to two A. C. cycles, the point K being six units above the base line. This permits the light spot to scan the lower film frame in the third field scanning period and to continue with the scansion of the upper film frame during the fourth field scanning period.

The ordinate KM terminates the line HK at the end of the fourth field scanning period and drops the light spot for the second scansion of the upper film frame by decreasing the light admitting openingto a value one unit high, denoted by MM', From M an oblique line MN is drawnin which N is three units higher than point M, in order to increase the regulating light in intensity sufficiently to eiect another upward movement of the light spot by a distance h. The point N terminates that portion of the opening 26a which corresponds to Period I in Fig. 4; this contour being repeated in cycles corresponding to each transit period. The contour of a transit Aperiod in Fig. 3 is, of course, laidoii. in sectors on disk 26; the number of sectors being at least two where interlacing is practiced,` as hereinafter more fully explained.

To achieve interlaced scanning, the light spot is given a small shift up (or down, as the case l may be) equal to half the width of a scanned line with every other field scanned. 'I'his is effected by generating a fiat topped line shifting current ofiield frequency, which, in this case, is

60 cycles per second; such current being applied to the plates 23 an'd 24 along with the light spot shifting'current from amplifier` 25. This current is generated by providing a series of rectangular 39 in Figs. 1 and 3; the openings being shown by f way of example as placed below both the opening 28a and slots.86. In Fig. 3, such openings corresponding to a' transit period in length, each opening being of constant width and of a length equal to one field-scanning period. 'I'hey admit light from a source 30" that is projected into a photocell 40 that is connected to an amplifier 4| which generates the desired line shifting current. By this means, the second scansion of the lower film frame does not have the lines put in the same as in the scansion effected during -the first field-scanning-period, but is shifted to start at a point between lines, as shown in Fig. 2, where the series of lines put in, in the lower film frame during vthe first eldscanning period are denoted a. The shifting potential which retains the light spot in the a position is'generated by regulating light, admitted byl of regulating light by the block b in Fig. 3. In'

the third field-scanning period, opening a'f admits regulating light to cause a shift that again puts in the a series of lines in the lower frame of Fig. 2, the block b" causing a shift that putsv in a series of lines b in the upper frame of Fig. 2 during the fourth field-scanning period. After this, the opening a'" admits regulating light that puts in a series of lines a in theupper frame of Fig. 2. From this, it is seen that Period II is not started by putting in a series of lines a, as was Period I, but instead by putting in lines b. Periods I and H are thus complementary and have alternatively different starting points.

In the drawings, it is seen that conductors 42 and 43 are provided to impress on the carrier oscillator i 8 impulses from saw-toothed wave generator 20 and line shifting amplifiers 25 and 4| in order thatthey may be broadcast with the picture signal for synchronizing purposes.

In operationf it is seen that the film I0 is caused to move downwardly at a constant rate across the scanning light spot on the end of tube I3, which spot is gradually moved upwardly against the motion of the film and then dropped to` a new starting position at recurring intervals. The modulated light resulting is projected into Dhotocell IB to modulate the carrier that is broadcast from the antenna I3.

denly downward at intervals of 60th of `a sec` ond by means of impulses that change every Vmth of a second and are optically produced by the opening 23a.

From the arrangement shown, it is seen that while the eect is to scan 24 film frames each. second, there are actually .60 fields scanned perv second, the iilm frames being scannedin pairs during the transit periodv which is lgth of a sec-- Aond in duration. During this period one film frame of the pair traversing the scansion field is scanned three times while the other is scanned twice. In thisway, the' desired standard number of film frames may be transmitted and reproduced at. the receiving station. At the re-v ceiving station, the scansion may be effected by the same method as in transmitting and the picture viewed directly on a uorescent screen of a receiving cathode rayv tube, or another nlm may be exposed to the image on the tube -while being moved continuously and synchronously with that at the transmitter. The film thus made is developed and projected on a viewing screen.

Where it is desired to execute interlaced scansion of a field with 343 linesor 1711/2 lines per iield scansion, the saw-toothed oscillator is arranged to supply oscillating current of a frequency of 10290, the screen' 26 being suitably perforated to achieve this. As a result, it is seen that a field scansion is either begun o r ended with a half line so that the light spot is already shifted to another starting position without the use of openings 39, as will be readily understood.

The oscillating amplifiers and 4l, while arranged to give only 60 cycle currents, should, of course, be designed to handle currents of very much higher frequency in order to have a safe margin for operation with constancy and delity. For example, such amplifiers may be made to accommodate frequencies of 6000 cycles per second.

The optical system of the scansion current generator, comprising light source, slit 29', opening in screen 26 and photocell, may, of course,

`and preferably does include one4 or more lens systems, the showing of such being omitted from the drawings in the interest ofsimplicity and clearness of illustration. Such system may also includeone or more alignment adjusting means, associated with its elements, such as a micrometer screw, applied in a manner well .known in the optical art. The slit 29' in such case has each controlling part independently adjustable in a lateral direction and may also be vadjustable in width, such devices being employed in the interests of rennement and precision but in no way affecting the principles of the invention as herein set forth.

Also, it will be seen that other sets of slots may be provided on the oscillation generator disli for producing other characteristics in the scansion current supplied, for example, a set of slots may be provided additionally' for extinguishing the light spot during the back stroke as it returns to start another line.

Since certain changes in carrying out the above process and in the constructions set forth which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described my invention what I claim4 as new and desire to secure by Letters Patent is:

1. Apparatus for scanning a picture film in4 facsimile transmission comprising, in combination, means including' a cathode ray tube having a screen impinged byja cathode ray to provide a scansion field having a. scanning light spot over which the lm is moved, means including an actuating 'eld for'ccntinuously. moving said nlm over said scansion neld at a rate which passes a desired number of frames in 'a period which is a multiple of an actuating eld cycle, a tube oscillator for supplying current to said cathode ray tube for deecting the cathode ray in a direc- 5 tion and at a. frequency suitable for line scanning, a second tube oscillator for supplying current to said cathode ray tube for shifting said ray so as to advance over the lm during said nlm motion in a manner'which completes the scanning of a frame in a desired period, photoelectricdevices for actuating said oscillators, a moving light regulating screen for said photoelectric devices, and means for moving said screen under the control of said actuating eld; the regulation of said screen being correlated with the frequency of said actuating iield to givev a scanning effect at a standard frame frequency.

2. Apparatus for scanning a picture lm in facsimile transmission comprising, in combination, means including a a screen impinged by a cathode ray to provide a eld having a scanning light spot over which the film is moved, means including an alternating current motor for continuously moving said film over said field at a rate which passes a desired number of frames in a period which is a multiple of an A. C. cycle, a tube oscillator for supplying current to said cathode ray tube foi` deilecting the cathode ray in a direction and at a frequency suitable for line scanning, a second tube oscillator for supplying current to said cathode ray tube for shifting said ray so as to advance over the film during said lm motion in a manner which completes the scanning of a frame in a tion,means including a cathode ray tube having a screen impinged by a. cathode ray to provide a ileld having-a scanning light spot over which the film is moved, means including an alternating current motor for continuously moving said film over said field at a Irate which passes a desired number of frames in a period which is a multiple of an A. C. cycle, a tube oscillator for supplying current to said cathode ray tube for deilecting the cathode ray in a direction and atafrequency suitable for line scanning, a second tube oscillator for supplying current to said cathode ray tube for shifting 'said ray so as to advance overl the film during said lm motion in a manner which completes the scanning of a frame in a desired period, a controlling photoelectric cell connected to each of said oscillators, a light screen having a continuous opening of a recurrent serrated pattern for regulating the light to the photoelectric cell controlling the line shifting oscillator and a series of discontinuous openings for controlling the line scanning oscillator, and a synchronous alternating` current motor for moving said light screen and having its poles chosen to impart motion at a rate which eects a desired correlation between said oscillators and the alternating current frequency.

t. Apparatus forscanning a picture lmin facsimile transmission comprising, in combination, means including a cathode ray tube having a screen impinged by a cathode ray to provide a field having a scanning light spot over which the 'i'llm is moved, means including an alternating current motor for'ccntinuousiy moving said nlm cathode'ray tube having over said field 'at a rate which passes a desired l number of frames in a period which is a multiple of an A. C. cycle, a tube oscillator for supplying y for shifting said ray so as to advance ovex` the film during said film motion` in a manner which completes the scanning of a frame in a desired period, a third tube oscillator for supplying a shifting potential with the scansion of alternate l frames whereby interlaced scansion may be effected, a controlling,photoelectric cell connected to each of said oscillators, a light screen having a series of equally spaced openings occurring at predetermined intervals that regulate the light to thecell of said rst tube oscillator, a continuous serrated opening arrangedto regulate the light to the cell of said second tube oscillator, another series of openings that regulate the light to the cell of said third tube oscillator, and a synchronous alternating current motor 'having its pairs of poles chosen in number such as to movesaid screen at a rate which gives an oscillating current that scans the frames with a frequency that is a multiple of the available alternating current frequency and shifts across frames and effects interlacing with a frequency based on the alternating current frequency.

5. In television scanning systems, apparatus for energizing the deecting means of a cathode ray tube which comprises, in combination, a tube oscillator adapted to supply the oscillatingcurrent,v a photoelectric cell connected to control said oscillator, a screen having an opening of an irregular serrated pattern for admitting light to said cell, said irregularity in the pattern recurring cyclically, and a synchronous alternating current motor for rotating said screen.'

6. Apparatus vfor scanning a picture lm'in facsimile transmission comprising, in combination, a means including a cathode ray.tube having a screen impinged by a cathode ray to provide a iield having a scanning light spot over which the lm is moved, means including an alternating current motor for continuously moving said film over said field at a rate which passes a desired number of frames in a period which is a multiple of an A. C. cycle, a tube oscillator for supplying current to said cathode ray tube for deiiecting the cathode ray at a frequency of 10,260 cycles per second and in a direction suitable for line scanning, a connected'series of cascaded ampliiiers supplying respectively the 19th, 9th and 3rd harmonics, a second tube oscillator for supplying current to said cathode ray tube for shifting said ray so as to advance over theilm during said film motion in a manner which completes the scanning of a frame in a desired period, a controlling photoelectric cell adapted to trigger oii the 3rd harmonic amplifier and a second controlling photoelectric cell connected to said second oscillator, a light screen having a continuous opening of a recurrent serrated pattern for reguf latingthe light to the second mentioned photoelectric cell controlling the line shifting oscillator and a series of discontinuous openings for controlling light impulses into the rstv mentioned photoeiectric cell at a 60 cycle fundamental frequency for controlling the line scanning oscillator, and a synchronous alternating current motor for movingV said light screen and having its poles chosen to impart motion at a rate which effects a desired correlationbetween said oscillators and the alternating current frequency.

7. Apparatus for., scanning a picture lfilm in facsimile transmissioncomprising, in combination. means including a cathode ray vtube having a screen impinged by a cathode -ray .to provide a scansion field having a scanningline spot over which the film is moved, means including an actuating field for continuously moving said film over said scansion field at a rate which passes a desired number of frames in a period which is a multiple of an actuating field cycle, means for deecting the cathode ray in a direction and at a frequency suitable for line scanning, a tube oscillator for supplying current to said cathode ray tube for shifting said ray so as to advance over the filmduring said film motion in a manner which completes the scanning of a screen in a desired period, a photoelectric cell connected to control. said oscillator, a screen having an opening of an irregular serrated pattern for admitting y light to said cell, said irregularity in the pattern recurring cyclically, and a synchronous alternating current motor under the control of said actuating field for rotating said screen, the light regulation produced by said screen being correlated with the frequency of said actuating eld to give a scanning effect at a standard frame frequency.

8. Television nlm-scanning apparatus which comprises anim-feeding mechanism adapted to feed a film longitudinally at a uniform speed and selected film-frame frequency, a scanning device positioned and associated in cooperative relation with said film-feeding mechanism, means associated with said scamiing device for producing atwo-dimensional scanning pattern of fieldscanning frequency adapted to scan a scanning area in the path of travel of said film both laterally and longitudinally of said film in lines extending laterally thereof, said field-scanning frequency being different from said film-frame frequency, and means for cyclically and successively associating the scanning pattern with scanning areas in the path of travel of the film having a plurality of respective displacements in the same direction within a cycle, said dis placements with respect to the scanning arcas of the corresponding immediately preceding field scansions being substantially different from the yheight of the scanning area that the longitudinal rate of scanning is adapted to produce in a complete eld-scanning period and being selected to compensate for film movement` and cause field scansions to register with respective film frames.

9. Television film-scanning apparatus which comprises a film-feeding mechanism adapted hto feed a film longitudinally at a uniform speed and selected film-frame frequency, a scanning device positioned and associated in cooperative relation with said film-feeding mechanism, means associated with said scanning device for producing a two-dimensional scanning pattern of fieldscanning frequency adapted to scan a scanning area in the path of travel of said .film both laterally and longitudinally of said -film in lines extending laterally 'thereof,' said field-scanningA frequencyrbeing different from said film-frame frequency, and means for cyclically -and sucpreceding scanning-areas by a substantial amount and to compensate for lm movement and cause field scansions to register with respective lm frames.

10. Television film-scanning apparatus which t comprises a film-feeding mechanism adapted to feed a film longitudinally at'a uniform speed and selected nlm-frame frequency, a scanningdevice positioned and associated in cooperative relation with said film-feeding mechanism, means associated with said scanning device for producing a two-dimensional scanning pattern of eldscanning frequency adapted to scan a scanning.

area in the path of travel of said film both laterally and longitudinally of said film in lines extending laterally thereof, said field-scanning frequency being different from said film-frame Yfrequency and the longitudinal scanning being opposite to the direction of movement of the lm, and means for cyclically and successively associating the scanning pattern with scanning areas in the path of travel of the film having a plurality of respective displacements, with respect to the scanning areas ofthe corresponding immediately preceding field scansions, in the direction of travel of the lm Within a cycle, the displacements between said scanning areas being selected to compensate for film movement and cause iield scansions to register with respective film frames,

11. Television nlm-,scanning apparatus which comprises a nlm-feeding mechanismadapted-to feed a film longitudinally at a uniform speed and 'frames are scanned in a plurality of eld scansions, the longitudinal scanning being opposite to the direction of movement of the film and the difference between the distance the film moves in a field-scanning period and the height of a scanning area that the longitudinal rate of scanning is adapted to produce in a complete fieldscanning period being substantially' different from said height, and means for cyclically and successively associating the scanning pattern with scanning areas in the path of travel of the nlm having a plurality of respective displacements within a cycle, with respect to the scanning areas of the corresponding immediately preceding field scansions, which are substantially dierent from the height of the scanning area that the longi tudinal rate of scanning is adapted to produce in a complete field-scanning period, said lplurality of displacements being selected to compensate for film'movement and cause eld scansions to register with respective film frames, said means for producing a two-dimensional scanning patterri and said displacements being correlated to scan different interlaced sets of lines of the film frames which are scanned in a plurality of eld scansione.

12. Television nlm-scanning apparatus which comprises a nlm-feeding mechanism constructed.

and adapted to feed a nlm at a uniform speed of substantially 24A Bim-frames per second, a scan- Evill '.7 ning device positioned and associated in cooperative relation with said-fllm-feeding mechanism,

means associated with said. scanning device for producing a two-dimensional scanning pattern having a field frequency of substantially 'elds per second and adapted to scan a scanning area in the path of travel of the film both laterally and longitudinally of the film in lines extending laterally thereof, the longitudinal scanning being opposite to the direction of movement of the film and the longitudinal length of said scanning area being selected to traverse a film frame in a field-scanning period, and means for cyclically e and successively associating the scanning pattern with scanning areasin the path of travel of the film having a plurality of respective displacements within a cycle, with'respect to the scanning areas of the corresponding immediately preceding field scansions, which are substantially differentfrom the height of the scanning area that thelongitudinal rate of scanning is adapted to produce in a complete field-scanning period, said plurality of displacements being selected to Vcompensate for nlm movement and cause said scanning area to register three `timesl with alternate film frames and twice with the film frames therebetween. I

13. In'a television transmitter, film-scanning apparatus which comprises a film-feeding mechanism adapted to feed a film longitudinally at a uniform speed and selected film-frame frequency, a scanning device positicned and associated in cooperative relation with said film-feeding mechanism, means associated with said scanning device for producing a two-dimensional scanning pattern of field-scanning frequency adapted to scan a scanning area in the path of travel of said film both laterally and longitudinally of said film in lines extending laterally thereof, said fieldscanning frequency being higher than said nlmframe frequency and tjhe longitudinal scanning being opposite to the direction of movement of the film, and means for cyclically and successively associating the scanning pattern with scanning areas in the path of travel of the film having a plurality of respective displacements within a cycle in the direction ofmovement of the ilm,

said plurality of displacements being selected toy cause corresponding -scanning areas to overlap respective immediately preceding scanning areas by a substantial amount and to compensate for film movement and cause field scansione to register with respective film frames.

14. The method of scanning a film in television transmission which comprises feedinga lm'uniformly at a selected film-frame frequency, successively scanning two-dimensional scanning f areas in the path of travel of the film laterally 'and longitudinally in-laterally extending lines4 at,4

a selected field-scanning frequency different from said nlm-frame frequency to thereby scan respective film frames of the nlm, and cyclically shifting the scanning 4area for successive field scansions by a plurality of displacements in the same direction within a cycle, with respect to the scanning areas of respective immediately preceding fleld scansions, which are substantially dierent from the heightof the scanning area that the" longitudinal rate of scanning is adapted to produce in a complete eld-scanning period, said plurality of displacements being correlated with ythe 'film-frame frequencyv and the i'leldscanning frequency to compensate for film move;l ment and cause -field scansions to register with respective film frames.

15. The method of scanning a nlm in television transmission which comprises feeding a nlm at a uniform speed and selected nlm-frame frequency, successively. scanning two-dimensional scanning areas in the path of travel of the nlm laterally and longitudinally to scan corresponding laterally extending interlaced sets of lines of respective nlm frames, the neldfrequency of the scanning of said areas being higher than-the nlmframe frequency and the longitudinal scanning being opposite to the direction of movement of the nlm, and cyclically shiftingthe scanning area for successive neld scansions by a plurality of displacements within a cycle, with respect to the scanning areas of respective immediately preceding neld scansions, which arek substantially different from the height of the scanning area that the longitudinal rate of scanning is adapted to produce in a complete neld-scanning period, said plurality of displacements beingA correlated with the nlm-frame frequency and the neldscanning frequency to compensate for nlm movement and cause neld scansions to register with respective nlm frames.

16. The method of scanning a nlm in television n transmission which comprises feeding a nlm at a uniform speed and selected nlm-frame frequency, successively scanning two-dimensional scanning areas in the path of travel of the nlm laterally and longitudinally in laterally extending lines at a selected neld-scanning frequency higher than said nlm-frame frequency to thereby scan respective nlm-frames, the longitudinal scanning of said areas being opposite to the direction of movement of the nlm andthe difference between the distance the nlm moves in a neld-scanning period and the height of a scanning area that the longitudinal rate of scanning is adapted to produce in a complete neld-scanning period being substantially different from said height, and cyclically shifting the scanning area for successive field scansions by a plurality of displacements within a cycle, with respect to the scanning areas of respective immediately preceding neld scansions, which are substantially different from the height of thescanning area that the longitudinal rate of scanning is adapted to produce in a complete neld-scanning period, said plurality of displacements being correlated with the nlm-frame frequency and the neld-scanning frequency to compensate for nlm movement and cause field scansions tov register with respective nlm frames.

17. The method of scanning a nlm in television transmission which comprises feeding a nlm at a uniform speed of substantially 24 nlm-frames per second, successively scanning two-dimensional scanning areas in the path of travel of the nlm laterally and longitudinally in laterally extending lines at a neld-scanning frequency of substantially 60 nelds per second, the longitudinal scanning of said areas being opposite to the direction of movement of the nlm and the longitudinal ning is adapted to produce in a complete neldscanning period and being selectedto compensate for nlm movement and cause said scanning area to register three times with alternate nlm. frames and twice with the nlm frames4 therebetween.

18. The method of scanning a nlm in television transmission which comprises feeding a nlm at a uniform speed and selected film-frame frequency, successively scanning two-dimensionalscanning areas in the path of travelof the nlm laterally and longitudinally in laterally extending lines at a selected neld-scanning frequencyl higher than said nlm-frame frequency to thereby scan respective nlm-frames, the longitudinal scanning of said areas being opposite tothe direction of movement of the nlm, vand cyclically and successively shifting the scanning area in the path of travel of the nlm by a'plurality of displacements within a cyclein the direction of movement of the nlm, said displacements being selected to cause corresponding scanning areas to overlap respective immediately preceding scanning areas by a substantial amount and-to compensate for nlm movement and cause neld scansions to register with respective nlm frames.

19. In electronic nlm-scanning apparatus, the

combination which comprises an electronic scanning device, a nlm-feeding mechanism positioned to support a nlm in cooperative relation with said scanning device and adapted to feed the nlm longitudinally at a uniform. speed, means associated with said scanning device for scanning saidnlm at line-scanning frequency in Alines extending -,laterally of the nlm, denection means associated with said scanning device for defiecting an electronic beam therein to scan said nlm longitudinally, means for cyclically producing a plurality of successive longitudinal scanning waves which change abruptly from respective nnal values to a plurality of substantially different initial valueswithin a cycle, each of said plurality of waves extending throughout at least one neld-scanning period and changing gradually from an initial value to a nnal value, and means for impressing said longitudinal scanning `waves on said denection means to thereby produce two-dimensional scanning patterns successively associated with a plurality of scanning areas in the path of travel of the nlm, said different initial values being selected to associate said two-dimensional scanning patterns with scanning areas having a plurality of respective displacements in the same direction within a cycle.

20.A In electronic nlm-scanning apparatus wherein nlm frames are scanned at a neld frequency dinerent from the nlm-frame frequency, vthe combination which comprises a nlm-feeding mechanism constructed and adapted to feed a nlm longitudinally at a uniform speed and selected nlm-frame frequency, an electronic scanning device positioned in cooperative conjugate rela-A tion with the nlm in said mechanism, means associated with said scanning device for scanning said nlm at line-scanning frequency in lines ex.

tending laterally of the' nlm, denection means associated with said scanning device for scanning said film longitudinallymeans for cyclically producing a plurality of successive longitudinal sawout at least one neld-scanning period and having a plurality of substantially dinerent initial values within a cycle, and means -for applying said longitudinal sawtooth-scanning waves to said denection means to thereby produce two-dimensional scanning patterns successively associated with a plurality of scanning areas in the path of travel ofthe nlm during respective neld scanning assises scanning device, anim-feeding mechanism positioned to support a film in cooperativerelation with said scanning device and adapted to feed the film longitudinally at a uniform speed and selected nlm-frame frequency, means associated with said scanning device -for scanning said film at line-scanning frequency in lines extending' laterally of the fllm, deflection means associated with said scanning device for defiecting an electronic beam therein to scan said film longitudinally, means for cyclically producing a plurality of successive longitudinal sawtooth-scanning waves which change abruptly from respeca film longitudinally at a uniform speed, means tive final values to a plurality of substantially different initial values within a cycle, eachpf said plurality of waves extending throughoutat least one field-scanning period, and means for impressing said sawtooth-scanning waves on said deectionf means to scan the nlmopposite the direction of movement thereof during the neidscanning periods, the field-scanning frequency being higher than saidfilm-frame frequency and the difference between the distance the lm moves in a field-scanning vperiod and the height of a scanning area at the iilm which the longitudinal `rate of scanning is adapted to produce in a complete field-scanning period being substantially different from said height, said plurality of dierent initial values being selected to compensate .for the nlm movement and cause successive ileld scansions to register with respective nlm-frames.

22. In electronic nlm-scanning apparatus'th .I I

combination which comprises an electronic scanning device, a film-feeding mechanism positioned to support a film in cooperative relation with said scanning device and adapted to feed a film longitudinally at a uniform speed, means .associated with said scanning device for scanning said film at line-scanning Vfrequency in lines extending laterally of .the film, deiiection means associated with said scanning device for scanning said film longitudinally, means for cyclically producing a plurality 'of successive longitudinal sawtooth-scanning waves each extending throughout at least one field-scanning period and having a plurality of substantially different initial values, and means for applying said longitudinal sawtooth-scanning waves to said deection means to thereby produce two-dimensional scanning patterns successively associated with a plurality of scanning areas in the path of travel ofthe film during respective field scanning periods, the field vof movement -of the iilm,-said different -initial values being selected to associate said two-dimensional scanning patterns with scanning areas in the path of travel of the lm having a plurality of respective displacements within a cycle in the direction ofmovement of the lm and to compensate for film movement and cause eld associated with said scanning device for scanning said film at line-scanning frequency in lines ex-.

tending laterally of the film, deflection means associated with said scanning device for scanning said film longitudinally, means for cyclically producing a plurality of successive longitudinal sawtooth-scanning waves each extending throughout at least one eld-scanning period and havingv a plurality ofs'ubstantially different initial values, and means for applying said longitudinal sawtooth-scanning waves-to said deflection means to thereby ,produce two-dimensional scanning patterns successively associated with a plurality of scanning areas in the path of travel of the nlm during respective field-scanning periods, the iield frequency of said longitudinal sawtoothscanning waves being higher than said filmframe frequency and the waves being applied to said deflection means to produce longitudinal scanning of said scanning areas opposite to the direction of movement of the film, said dlierent initial values being selected to associate said two-dimensional scanning patterns with scanning areas in the path of travel of the film having a plurality of respective displacements within a cycle in the direction of movement of the nlm and being correlated with the longitudinal field scanning to cause a plurality of scanning areas to overlap by a substantial amount,whereby nlm positioned in cooperative conjugate relation with.' the iihn in said mechanism, means associated with said scanning device for scanning said film at line-scanning frequency in lines extending laterally. of the film, deflection means associated vwith said scanning device for scanning said film longitudinally, means for cyclically producing a plurality yof successivel longitudinal sawtoothscanning waves each extending throughoutk at least one field-scanning period and having a plurality of substantially diierent initial values to thereby produce scanning patterns occupying a plurality of non-contiguous p'ositions in the path ofjtrayel of the lm within a cycle, and means for applying said sawtooth-scanning waves to said deection means, the eld frequency of said sawtooth-scanning waves being substantially 60xiields per second and said plurality of different initial values being selected to compensate for iilmmovement and cause said scanning patterns to register three times successively with alternate iilm frames and twice successively with the iilm frames ,therebetween,

said means for scanning the film at line-scanningv frequency and said longitudinal Ysawtooth-scanningwaves being correlated'to scan a plurality of different interlaced setsJ of lines of each iilm frame during respective field 'scansions of the iilm frame.

25. In a television transmitter, apparatus forl scanning a continuously moving lm at a eld frequency higher than and a non-multiple of the film-frame frequency which comprises a filmfeeding mechanism adapted to feed a film longitudin'ally at a uniform speed and selected ilimframe frequency, a scanning device positioned and associated in cooperative relation with said erally thereof, said iield-scanning frequency being higher than and a non-multiple of said nlm-frame frequency and the longitudinal scanning being oppositeto the direction of movement of the, film, and means for cyclically and successively associating the scanning pattern with scanning areas in the path o! travel of the lm having a plurality of respective displacements within a cycle in the direction of movement of the film, said plurality of displacements being selected to cause corresponding scanning areas to overlap respective immediately preceding scanning areas by'a substantial amount and to compensate for nlm movement and cause field scansions to register with respective film frames.

` PETER C. GOLDMARK. 

